Path-Q Solar

How can weather records help determine whether lower solar production is normal?

Answer

Compare the affected production period with the same system's historical output and with weather data for the site, including cloud cover, precipitation, smoke, snow, temperature, and unusual storms. A weather-related reduction should generally align with the timing and severity of those conditions; a persistent decline during comparable weather is more suggestive of a system issue.

Key points

  • Use daily or hourly production data rather than only monthly totals.
  • Compare like-for-like periods and account for seasonal sun angle and day length.
  • Separate weather effects from outages, shading, soiling, curtailment, and inverter clipping.
  • Use weather records as supporting evidence, not as proof by themselves.

What it depends on

  • Reliable system production data
  • The system's prior baseline or a validated production model
  • Weather observations representative of the array's location
  • Snow, shading, outage, and maintenance records

Risks and trade-offs

  • A weather station several miles away may not represent local cloud or storm conditions.
  • A single cloudy day cannot establish a fault or normal performance.
  • Weather-normalized comparisons can be misleading if the system configuration or monitoring data changed.

Information you may need

  • The dates and magnitude of the production decline
  • Hourly or daily production and inverter-status data
  • Local records for cloud, rain, smoke, snow, and temperature
  • Any records of outages, cleaning, shading changes, or equipment work

Your next step

What to do next

Create a date-matched comparison of production, system status, and local weather for affected and unaffected periods, then have a qualified provider review unexplained deviations.

Path-Q

Find the right next step

Answer a few questions and we’ll narrow your options.

Loading…

SQ02004